Interspecies Attachments

Why Different Animals Form Bonds

The improbable relationship between Owen, a baby hippo orphaned by the 2004 tsunami in Southeast Asia, and Mzee, a 130-year-old tortoise living in Africa, made headlines for its remarkable and touching story. Following the disaster, the displaced hippo was moved to LaFarge Eco Systems, a wildlife refuge in Kenya, and quickly bonded with the giant tortoise.

Many reports of similar unexpected unions have made the news in recent months, from a rodent-eating snake and a hamster living in harmony in a Tokyo zoo to a puppy serving as a socialization tool for a lion cub separated from his mother. And though most of these situations are happening in captivity, similar introductions have been made in the wild. When a deer was killed near Natural Bridge, Va. last year, her fawn moved onto a nearby pasture occupied by a cow and her calves. The cow soon began looking after the fawn as if she was the natural mother.

"In many instances, these cases have their origins in a young animal who has not been weaned taking to an older animal," says Animal Welfare Institute Laboratory Animal Consultant Viktor Reinhardt, a veterinarian. "Under natural conditions, this is the mother." However, sometimes animals are forced to adapt.

This is certainly true in the case of Owen and Mzee. "Owen saw Mzee as his refuge," says LaFarge Eco Systems General Manager Paula Kahumbu. "Mzee is a social tortoise who had been looking for closer companionship, which he lacked from the other animals already present in his enclosure…. It's a two-way relationship that really works."

Though the refuge has attempted to reunite Owen with other hippos, he continues to prefer the company of Mzee. This "imprinting" is a long-accepted concept that endures despite animals' differences, Reinhardt said. "It's a special phenomenon in that it is irreversible." Not only does Owen feel a stronger connection to Mzee than other hippos, but he may prefer to be around tortoises for the rest of his life.

In other cases, different species connect after the loss of a mate. "It's amazing what animals do when they want to bond and be close to each other," says Mark Bekoff, a professor of Ecology and Evolutionary Biology at the University of Colorado.

Recently at the Los Angeles Zoo, a Red River porcine named Willy began nuzzling up to a bongo (a large, forest-dwelling antelope) named Nicole after his mate died of cancer last summer. Together in the mud pit, they take naps side-by-side and groom each other. To the animals' caretakers, it's obvious that Willy was lonely and wanted to make a new connection. "We do it and so do they," Bekoff says.